[Bug]: Swift support does not build with Xcode 11

[rec0de]

What are the steps to reproduce this issue?

1. Switch to Xcode 11.7, following arm64e deployment docs
2. (optional) uninstall & re-install theos
3. Create new project using iphone/application_swift template (which targets iOS 12.2 by default)
4. run make package

What happens?

The build fails while building swift support tools (see output below)

What were you expecting to happen?

Build should complete with no errors, as with current Xcode toolchain.

Paste any relevant logs, error output, etc.

==> Notice: Build may be slow as Theos isn’t using all available CPU cores on this computer. Consider upgrading GNU Make: https://theos.dev/docs/parallel-building
> Making all for application TheosTest…
==> Building Swift support tools…
/Users/x/theos/vendor/swift-support/Sources/SwiftcOutputParser/main.swift:101:1: error: expected expression
@rethrows protocol RethrowingGet {
^
/Users/x/theos/vendor/swift-support/Sources/SwiftcOutputParser/main.swift:107:23: error: 'rethrows' function must take a throwing function argument
    func rethrowGet() rethrows -> Success {
                      ^
/Users/x/theos/vendor/swift-support/Sources/SwiftcOutputParser/main.swift:125:16: error: call can throw, but the error is not handled; a function declared 'rethrows' may only throw if its parameter does
    return try result.rethrowGet()
               ^

Failed to build swift-support: command failed: SPM_THEOS_BUILD=1 swift build -c release --package-path /Users/x/theos/vendor/swift-support --build-path /Users/x/theos/vendor/swift-support/.theos_build
make[2]: *** [internal-TheosTest-swift-support] Error 2
make[1]: *** [before-TheosTest-all] Error 2
make: *** [TheosTest.all.application.variables] Error 2

Additional context

Using Xcode 11.7 is the recommended way to build apps for iOS 12-13 due to the ABI changes - but I can't seem to get any builds for these versions to work, even with the Xcode 11 toolchain.

What OS are you seeing the problem on?

macOS

What OS version does it have installed?

14.5

What toolchain and version are you using?

Xcode 11.7

Which SDK version are you using?

iOS 16.5

What OS is your client device running?

iOS

What OS version does it have installed?

iOS 13.3

Which device model is it?

iPhone 11

Which jailbreak is it using (if relevant)?

No response